Navigation device



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- 3,043,907 NAVIGATIN DEVICE Weslye L. Martin, Hasbrouck Heights, NJ.,assigner to The Bendix Corporation, a corporation of Delaware Filed Jan.19, 1950, Ser. No. 139,377 8 Claims. (Cl. 178-6.8)

The invention relates to navigation systems, and more particularly to anautomatic navigation device in which one or more celestial bodies may beused as a reference.

One object of the invention is to provide a celestial navigator forautomatically guiding ships, aircraft or other moving vehicles on aprescribed course.

nited States Patent Another object is to provide a device for indicatingthe location of the ship, aircraft-or other on which the device ismounted.

A further object is to Vprovide a relatively simple celestial navigatorof high accuracy.

Another object is to provide a device ywhich automatically selects thebrightest reference within a relatively broad field and centers thedevice on the reference.

moving vehicle Another and still further object is to provide a novelamplifier which selectively passes the greatest signal amplitude andsuppresses or discriminates against lesser signal amplitudes.

A still further object is to provide a plurality-of amplifiers gated byvoltages synchronized with the horizontal and vertical sweep voltages todistinguish portions of the signal corresponding to the severalquadrants of an image of the iield.

i L FIGURE 6.

The invention contemplates a television camera including means, such asa telescope, or lens, directed to a reference in a contrasting iield andproviding an image of the field. `Scanning means energized by sweep-voltages causes the electron beam from a pickup tube to scan the imageand the pickup tube produces an electrical signal corresponding to theimage.

A plurality of amplifiers responsive to the signal are gated insynchronism with the scanning means to alternately pass and lblock thesignal. Each of the amplifiers passes the signal corresponding toone-half of the image and blocks the'signal corresponding to the otherhalf of the image; that is, one amplifier passes the signalVcorresponding to the upperhalf .of the image, a second amplifier passesthe signal corresponding tothe lower half-,of the image, a `third.ampliier `passes `the signalv output of the third and fourthampli-tiers directs Vthe viewing means about mutually perpendicular axesto the' reference.

To detect the brightest reference'in the lield, the signal -and a secondservo system responsive to the differential from the television cameramay be impressed on a se- .lective amplifier which ampliiiesthelargestsignal amplitude corresponding to the brightest reference andsuppresses or discriminates againstsmallersignal amplitudescorresponding to weaker references." The modifiedV signal above;Aftenthe viewing means iscentered onpthe brightest image in" the held bythe servo; systemLthe viewing means may be adjusted, as by changing thefocal Iengh l of the lens system, to

` 'I'he foregoing and otherl objects and` advantages of 'theinventionwillappear. more. fully hereinafter from a consideration A.ofthe detaile'ddescription which follows,

takentogether with the accompanying drawingsV wherein further magnifythelimage p fthen' is impressed 'on the gated` amplifiers as described WFIGURE 3 shows an image of an instantaneous field with three references.

FIGURES 4 and 5 show the wave forms of the horizontal and vertical sweepvoltages for scanning the image of FIGURE 3. f 1

FIGURE A6 shows the signal wave form for one scansion ofthe image ofFIGURE 3. Y,

FIGURES 7A and 7BY show the square wave voltages for gating the left andright gated amplifiers to alternately block and pass the signal shown inFIGURE 6.

FIGURES 8A and 8B show the square Ywave voltages for gating the Aup anddown gated am-pliers to alternatively block and pass the signal shown inFIGURE 6.

FIGURES 9A and 9B show the outputs of the left and. right gateamplifiers -in responseY toV the signal VVof FIGURES 10A and 10B shewthe outputs er the up FIGUREG'.V A Y FIGURE 11 shows an image of the eldwith the brightest reference image centered inthe field.

YReferring now toY the `drawings for a more detailed `descriptirnr ofthe lnovel navigation device of the present invention, the device is`shown in FIGURES land 2 as including a television camera VIl rotatableabout mutually perpendicular axes and which may correspond generally toAirborne Conversion Unit PH-548/AXT2A. The camera may include atelescope lens system` 5 directed to a selected field, having one ormore references R, R', R" of different intensities, and providing animage of the iield, as shown in FIGURE 3. A scanning system 7 'providesAhorizontal and vertical sweep voltages,

as shown lin FIGURES 4 and 5, to the electron-beam `of a pickup tube 3,such asA an image orthicon, for scanning the image, and converts theimageto an electrical signal shown in FIGURE 6.V The resultingelectrical signal is amplified hya video amplifierv 9.

A selecting amplier 11 receives the amplified signal frornvideoamplifier 9 and ampliiies the largest 4signal amplitude corresponding tothe brightestv reference R (FIGURE 3) and discriminates in successivelstages against the smaller signal amplitudes corresponding to .weakerreferences R', R", and which are suppressed or are not amplified to thesame extent as the largest `signal amplitude.

The selective amplifier includes a rectiierv 13hconnected through acondenser'19 to the grid 15 of a pentode 17. Rectier 13 Vmay be `ofgermanium, silicon, selenium, copper oxide, etc., andV has a non-linearresistance voltage characteristic so that it Foffers a lower resistanceto positive signals ofone or two volts than :for smaller positivesignals or negative signals. `This non-linear characteristicfprovidesfor the passage`-offpositive signals Vin theafbove range and thepartial` or'jco'mple'te` fblo'cking of all other less positive ornegative signals. vRectifier' 13 provides the yirst stage of`discrimination by passing -to grid'15 .only positive signalsgreaterfusually'hy one or two volts) than the positive biasof'potentiometer 21; Grid 15 is connected to ground through a'rectier23, similar to rectifier 13, which prevents the grid from assuming aVnegative potential relative to ground.

Plate 25 of tube 417 is 'connected' through a condenser Patented JulyI0, 1962 27, a rectier 29, and a` bias potentiometer 31 to ground andthrough condenser 27 and a rectifier 33 to the control grid 35 of apentode 37. Potentiometer 31 and rectifier 29 maintain the char-ge oncondenser 27 at a pre-V determined potential to maintain the signalpulse correspending to the reference at a uniform amplitude. Also,rectifier 33 provides the second stage of discrimination by passing onlynegative signals and by attenuating smaller signal amplitudes to agreater extent than the larger signal amplitudes to increase theamplitude difference.

A cathode follower and rectifier including a double triode 39 providesthe final stage of voltage discrimination. The twice-discriminatedamplified output of pentode 37 is impressed on bot-h grids 41, 43 ofdouble triode 39, and a voltage develops across a resistor 45 connectedto the cathode 47 of tube 39. A condenser 49 is charged through arectifier 51 by the voltage across resistor 45 in response to peaksignal amplitudes corresponding to the brightest reference. Rectifier 51provides for current flow while charging condenser 49 and substantiallyprevents discharge of condenser 49 ibetween the charging pulses.

The charge on condenser 49 is proportional to the largest signalamplitude and the voltage across the c011- denser is applied through aresistor 53 to the cathode 55 of double triode 39. Plate 57 of doubletriode 39 is connected to grids 41, 43 so that one-half ofthe doubletriode 39 acts as a rectifier. Current flows from cathode 55 throughresistor 53 to condenser 49 only when the signal amplitude exceeds thevoltage of condenser 49- Vthat is, for the Vbrightest reference in thefield. The output of the rectifier portion of tube 39 is impressedthrough a coupling condenser 59 on `grid 61 of an amplifier tube 63, andthe output of tube 63 is further amplified by a tube 65.

The discriminated amplified signal is impressed Von suppressor grids 77,79, 81 and 83 of tubes 85, 87, 89 and 91 of a left gate amplifier 93, aright gate amplifier 95, an up 4gate amplifier 97 and a down gateamplifier 99, respectively.

A square wave generator 101 is synchronized with scanning system 7 andproduces a square Wave voltage (see yFIGURE 7) having the same frequencyas the horizontal sweep voltage. One phase of the square wave voltage isshown in FIGURE 7A, and is applied to the control grid 103 of tube 85 ofleft gate amplifier 93 and the 'opposite phase of the square wavevoltage is shown in FIGURE 7B and is applied to control grid 105 of tube87 of right gate amplifier 95. The' square wave voltage from generator101 is synchronized with the horizontal sweep voltage so that the squarewave voltage changes polarity when the electron sweep of the imageorthicon is on the vertical center line X of the eld image. The squareWave voltage gates amplifiers 93, 95 so that the output of left gateamplifier 93 (FIGURE 9A) corresponds to the portion of the signalrepresenting the left half of the field image-that is, the portion tothe left of the vertical center line X, as viewed by the image orthicon,and so that the output of right gate amplier 95 (FIGURE 9B) correspondsto the portionV of the signal representing the right half of the fieldimage-that is, the portion of the image to the right of the verticalcenter line X, as viewed by the image orthicon.

The output voltages of left `gateV amplifier 93 and right -gateamplifier 95 are fed to left and right integrating rectifiers 107, 109.Each integrating rectifier includes a rectifierV triode 113 having itsgrid 115 connected to its plate 117. The output voltage from theassociated gated yamplifier is fed to'ca'thode 111 of triode 113 and therectified voltage is integrated by an integrating circuit in the platecircuit including a resistor 119 and a condenser 121 in paralleltherewith. The integrating circuit requires several signal pulsescorresponding to several'completeV scansions of the field image tocharge condenser 121.

Modulators 125, 127, are controlled by the rectified integrated outputsof integrating rectifiers 107, 109, respectively. Opposite phases of acarrier voltage from an alternating power source 129 are applied tomodulators 125, 127 and the differential output of the modulators isamplified by a power amplifier 2139 (FIGURE l). The amplifieddifferential output of modulators 125, 127 is impressed on the Variablephase stator winding 133 of a motor 135 for driving camera 1 in azimuthabout a vertical axis. The fixedphase 137 of motor 13S is energized bythe second phase of power source 12,9.

When the brightest reference image Ris to the left or to the right ofthe vertical center line X of the field image, the differential outputof modulators,125, 127 either lags or leads the voltage from power,supply `12.9 by 90, as determined by the direction of displacement ofthe reference image from the vertical center line, whereupon azimuthmotor 13 5 rotates camera 1 tothe left or to the right until thereference image vis aligned with the vertical center line, as shown inFIGURE 11, whereupon the differential output of modulators 12,5, 127drops to zero and azimuth motor 135 stops.

A square wave generator 139 is synchronized withA the scanning systemand produces a square wave voltage (FIGURE 8) having the same frequencyas the vertical sweep voltage (FIGURE 5). One phase of the square wavevoltage shown 4in FIGURE 8A is applied to'up gate amplifier 97V and theopposite phase of the square wave voltage shown in IFIGURE 8B is appliedto down gate amplifier 99. The square Wave voltage from generator 139 issynchronized with the vertical sweep voltage so that the square wavevoltage changes polarity when the electron sweep of the image orthiconis on the horizontal center line Y of the field image. The square wavevoltage gates amplifiers 97, 99 so that the output of up gate amplifier97 corresponds to the portion of the signal above the horizontal centerline, and so that the output of down gate amplifier 99 corresponds tothe portion of the signal below the horizontal center line. The outputvoltages of up gate amplifier 97 and down gate amplifier 99 are fed tointegrating rectifiers 141, 143, and their outputs control modulators145, f147 excited by opposite phases of the carrier voltage fromalternating power source 129. The differential output of modulators 145,147 is amplified by a power amplifier 149 and the amplified output isimpressed on the variable phase stator winding 151 of a motor 153 fordriving camera 1 in elevation about a horizontal axis. The fixed phaseof motor 153 is energized by power source 1129.(

When the brightest reference image R is above or below the horizontalVcenter line, the differential output of modulators 145, 147 either lagsor leads the voltage from power supply 129 by 90, as determined by thedirection of displacement of the brightest reference image from thehorizontal center line, whereupon elevation motor 153 rotates camera 1upwardly or downwardly until the reference image is yaligned with thehorizontal center line, `as shown in FIGURE l1, whereupon thedifferential output of modulators 145, v147 drops to zero and elevationmotor 153 stops.

After the camera is centered onthe brightest reference R in the field,the lens system 5 of the telescope may be changed to increasemagnification of the image field, and thereafter, the device will moreaccurately maintain the selected reference imagecoincident with theintersection of vertical and horizontal center lines X, Y.

A suitable indicator (not shown) may be provided to indicate the angularbearing of the camera relative to a reference index and by providing twovsuch devices directed to different stars the' position lof the craftmounting -the devices may be determined automatically at all times.

Also, instead of driving the camera in azimuth and elevation relative tothe craft on which the device is mounted, the camera may be fixed to thecraft and the azimuth and elevationy motors may be drivngly connected tothe sweep voltage, a second pair of amplifiers receiving the modiiedsignal and gated by opposite phases of the second reference voltage andalternately blocking and passing the modiiied signal, said secondreference voltage being synchronized with the horizontal sweep voltageso that one of said gated amplifiers passes the modified signal onlyduring scanning of the image at one side of a vertical center line ofthe image and so that the other gated ampliier passes the modifiedsignal only during scanning of the image at the opposite side of thevertical center line, a second pair of integrating rectiiiers receivingthe outputs of said second pair of gated amplifiers, a second pair ofmodulators energized by the alternating power source and controlled bythe outputs of said second pair of integrating rectiers, and a secondservo system responsive to the differential output of said second pairof modulators and arranged to direct said camera about a vertical `axisto the reference.

8. In a device of the kind described, a television camera adapted to bedirected to the brightest reference in a field and including scanningmeans energized by sweep voltages for scanning the image, said cameraproducing an electrical signal corresponding to the image, a selectiveamplifier adapted to increase the signal amplitude corresponding to thereference and to suppress the signal amplitudes corresponding to theremainder of the iield, said selective amplifier including va rst stageof discrimination having a rectiiier with non-linear resistance voltagecharacteristics and with an input terminal for receiving the signal andan output terminal maintained at a predetermined potential so that saidrectiier passes only peak amplitudes in excess of the potential, a iirstamplifier for amplifying the peak signal amplitudes passed by saidrectier, a second stage of discrimination including a rectifier having anon-linear resistance voltage characteristic and receiving the output ofsaid first ampliier and passing peak signal yamplitudes `anddiscriminating against lesser signal amplitudes, .a second amplierreceiving the output of saidsecond rectifier, yand a third stage ofdiscrimination including a third rectiiier having an input terminalreceiving the output of said second amplifier and having an outputterminal, and means responsive to the output of said second amplier formaintaining the output terminal of said third rectifier at apredetermined potential so that said third r'ectier passes signalamplitudes only in excess of said potential, a plurality of means gatedin synchronism with the scanning means for alternately passing andblocking the output of said selective ampliiier, each of said meanspassing the output of said selective arnplifier corresponding toone-half of the image and blocking the output of -said selectiveamplifier corresponding to the other half of the image, and a servosystem responsive to the differential output of pairs of said gatedmeans for centering said camera on the reference.

References Cited in the tile of this patent UNITED STATES PATENTS`2,155,402 Clark Apr. 25, 1939. 2,403,387 McLennan July 2, l9462,403,975 Graham July 16, 1946 2,417,446 Reynolds Mar. 18,1947 2,424,193Rost et al. July 15, 1947 2,444,933 Iasperson July 13, 1948 2,448,007Ayres Aug. 3l, 1948 2,459,117 Oliver Jan. 11, 1949 2,480,868 MarshallSept. 6, 1949 2,520,932 Hoeppner Sept. 5, 1950 2,529,666Y Sands Nov. 14,1950 2,532,063 Herbst Nov. 28, 1950

